Wave energy converter with float

ABSTRACT

A device to convert vertical motion of waves in a body of water into useable work has hollow float ( 14 ) centrally mounted on vertical sleeve ( 16 ) sliding on fixed vertical shaft ( 10 ). Oscillations are converted into rotation via an opposing pair of pinion gears, transferring power from upstroke and downstroke respectively, by meshing with circular grooves ( 18 ) on sleeve ( 16 ). The device is protected from lateral and torsional forces of the waves by an encircling slotted wall ( 8 ). The float may be half filled with water to balance buoyancy and gravitational forces.

This invention relates to devices for converting the energy from wavesin body of water.

It is desirable to be able to convert kinetic energy from water motion(waves) and from gravity force into mechanical energy, by a device whichcan provide self-sustainable form of power generation into readilyavailable power source for further use.

In an order to fulfill above desire, the device has to function in anengine like manner. There have been many proposals to convert kineticenergy from water waves, but Prior proposals have not enabled this to bedone in satisfactory way.

Specifically, it has not been possible to readily use the power outputfrom these devices for the universal application. For an example, oneprevious device for conversion of wave power, known as “OscillatingWater Column” comprises of partially submerged open tubes. As the wavepasses, the water height within the tube changes, driving displaced airthrough turbine situated at the top of the tubes. Disadvantages in thisdevice is in its irregular volume of air supplied to turbines, itsdependency on large volume of displaced air needed to produce viablepower output and no storage of energy.

Another example is a barge, which receives water from the waves andguides the collected water to turbines. A disadvantage in this device isa very similar to O.W.C. Yet another example is a few proposals toposition a float in a body of water to reciprocate. Disadvantages inthese previous (“float”) devices are, lack of control to theyreciprocating strokes, unbalanced power output of each stroke where theforces of up and down strokes are not synchronized, total anduncontrollable exposure to sweeping power of waves and severely-harshweather, also, they have no storage of energy. All of these proposeddevices share the same or similar disadvantages, and as such they arenot an engines since they do not function like an engines.

If an energy conversion device is to function like an engine-it willhave to perform-contain three “fundamental elements”:

The first “fundamental element” is an energy-power source, to initiate amotion.

The second “fundamental element” is an energy-power source to maintain amotion.

And third “fundamental element” is storage of the energy for furtheruse.

These problems are overcome by the present invention, which is basedon/and contains all three “fundamental elements”, it is an engine.

This invention, Kinetic Engine, aims to provide a device to harness acombination of kinetic energy from motion of water (caused by waves) andpotential kinetic energy induced by gravity force. The invention providedevice for installation in body of water, comprising a fixed verticalshaft, a float mounted on the fixed shaft so as to allow verticalmovement therealong, such that the float is reciprocated verticallyalong the shaft by the alternate actions of buoyancy and gravity forcesas each wave passes the device, and power takeoff means driven byreciprocation of the float, wherein the float is surrounded by atubular, slotted wall which spreads water around the float to produceeven uplift and to shield the float from lateral and torsional forces ofeach wave.

In one embodiment, the power takeoff means includes means fortransferring the linear reciprocation of the float to a rotary outputshaft. Preferably, this means includes the pair of gears driven by arack connected to the float, each of the gears freewheeling when drivenin one direction and transferring power when driven in the oppositedirection, such that one of said gears transfers power to power outputmeans on an upstroke of the float and the other of said gears transferspower to said power output means on a downstroke of the float.Desirably, each of said gears drives a respective shaft, said shaftsbeing connected by further gears to provide a relatively smooth andcontinuous power output rotating in a single direction upon bothupstroke and downstroke.

Further preferred embodiments will now be described with reference tothe accompanying drawings, in which:

FIG. 1 is a schematic elevational cross section of the device;

FIG. 2A and 2B are schematic elevations showing operation of the deviceupon, respectively, upstroke and downstroke; and

FIG. 3 is schematic isometric view of a preferred gearbox arrangement.

With reference to FIG. 1, the device includes a tubular, slotted wall 8encircling a vertical shaft 10 having a base 12 embedded in the seafloor or otherwise fixed in position. The wall height is above expectedrange of wave peak and the shaft length extends over substantially theentire height of the wall

A float chamber 14 is mounted on a sleeve 16 which in turn is mountedfor sliding along the shaft. The float chamber may be constructed of anysuitably strong and corrosion—resistant material, for example metalalloys, fiberglass, molded plastics. or wood. The float chamber may beformed of single—piece construction with single or plurality ofcompartments to hold either, weight media/water, or air, or combinedwater and air.

The float chamber has an inlet/outlet 18 and closure on it uppersurface, through which the chamber is part filled with water drawn fromthe surroundings. Preferably, The chamber is approximately half filledwith water and reminder with air, whereby air can be filled atatmospheric or higher pressure. By adding or decreasing amount of liquidweight media/water inside the floats chamber, it is possible to balancebuoyancy and gravity forces for smooth reciprocating operation. Thefloat is preferably circular in plain view, preferably, spherical orellipsoidal in shape, so as to minimize torsion and lateral forces onthe device from the waves.

The float is furthermore protected from damage with surrounding tubular,slotted wall (FIG. 1) which shield the float from lateral and torsionforces from the wave without diminishing the wave height (rise of waterlevel) which drives the linear motion of the float. In anticipation ofextreme weather conditions and to prevent any possible damage to thedevice, the float can be flooded completely to send it to sea floor.

The water can be pumped out once the extreme conditions have passed.

As the water surface rises with the approach of a wave, the buoyancyforce, (it is the first of “fundamental element”—power source toinitiate a motion) lifts the float on the rising surface of the wave(FIG. 2A). At this point, the tubular, slotted wall which surroundingthe float (FIG. 1) is of crucial importance as it spread water aroundthe float to provide even uplift. The amounts of energy involved can beenormous.

As the wave peak passes, the weight of the float with weight media (thewater inside the float) momentarily are at a point of rest. This is thepeak of the upstroke and the point at which the gravitational potentialenergy is at its maximum. As the (outside) water level drops (see FIG.2B) the downward trust is produced by gravity force through the waterinside the float (it is the second “fundamental element”—power source tomaintain a motion) without the counteracting effect of buoyancy. Duringthe down stroke, the float loses potential energy and gains kineticenergy, which is converted by the device in to mechanical energy inlinear motion. Just before the float comes to rest on the water surfaceat the wave trough, the whole of the float's kinetic energy has beenconverted to mechanical energy, at this point a full energy conversioncycle is completed and the next cycle begins as the water surface rises.

In the illustrated embodiment, the sleeve 16 on which the float 14 ismounted extends above the float to provide a connection to the powertakeoff. Preferably, the upper portion of the sleeve has a series ofregularly spaced grooves 18 therein. This grooved portion 20 of thesleeve acts as a gear rack for the gear box 22 in FIG. 3, as discussedbelow. As the rack is cylindrical, it can rotate with any torsion forceapplied to the float, without transferring significant torque to geararrangement.

Referring to FIG. 3, a gearbox is provided to convert the linear motionof the float into rotation. The gearbox 22 has an opposed pair of piniongears 24 a, 24 b matching in profile and pitch with the rack, and eachmounted on a respective horizontal shaft 26 a, 26 b. Each pinion isclutch—or ratchet—mounted on the shaft so as to engage and drive theshaft when the pinion is rotated in the direction of the respectivearrow 28 a, 28 b, but to freewheel on the shaft when rotated in theopposite direction. Thus, when the float 14 and sleeve 16 are rising,pinion 24 a is driving its shaft 26 a anti clockwise (as shown in FIG.3), while pinion 24 b is freewheeling clockwise relative to its shaft 26b. When the float 14 and sleeve 16 fall, pinion 24 b drives shaft 26 bwhile pinion 24 a freewheels.

Shafts 26 a, 26 b may in addition have fixed gear wheels 30 a, 30 bjoined by a jockey gear 32. When shaft 26 a is being driven, the jockeygear 32 drives shaft 26 b in the same direction, and vice versa, suchthat each of the shafts rotates during both rising and falling of thefloat. Any one or more of shafts 26 a, 26 b or the jockey wheel shaft 34can be used as the power output shaft, to lead to a generator (notshown) or other power generation device. (this is the third of“fundamental element”—storage of energy for further use).

The gearbox arrangement of FIG. 3 is advantageous in that it is adaptedto cope with variations in wave amplitude, as distinct from a camarrangement which requires fixed amplitude.

In an unillustrated alternative, the reciprocation of the float andsleeve may drive a hydraulic or pneumatic ram.

While FIGS. 1 to 3 illustrate only a single device, it will beappreciated that a plurality of the devices can be linked to provide apower “farm”. The optimal size, mass and number of the devices may varybetween sites according to typical local ocean condition, for examplewave height and frequency.

As an alternative to installing the devices in a position where thewaves travel past the device, it will be more desirable, as it is idealfor, to be installed along a breakwater or other impediment to the wavetravel and be lifted by the surge produced as each wave strikes theimpediment.

While particular embodiments of this invention have been described, itwill be evident to those skilled in the art that the present inventionmay be embodied in other specific forms without departing from theessential characteristics thereof. The present embodiment and examplesare therefore to be considered in all respects as illustrative and notrestrictive, the scope of the invention being indicated by the appendedclaims rather then the foregoing description, and all changes which comewithin the meaning and range of equivalency of the claims are thereforeintended to be embraced therein.

The claims defining the invention are as follows:
 1. A kinetic enginefor installation in a body of water, including a fixed vertical shaft, afloat mounted on the fixed shaft and vertically movable therealong, suchthat the float is reciprocated vertically along the shaft by thealternate action of buoyancy and gravity forces as each wave passes thedevice, and power takeoff means driven by reciprocation of the float,wherein the float is surrounded by a tubular wall having a plurality ofopenings spaced evenly thereabout to spread water around the float toproduce even uplift and to shield the float from lateral and torsionforces of each wave.
 2. A kinetic engine according to claim 1 whereinthe float has a chamber/chambers adapted to be partially or fully filledwith water.
 3. A kinetic engine according to claim 1 wherein the floatmay be substantially filled with water to submerge the float.
 4. Akinetic engine according to claim 1 wherein the float has achamber/chambers adapted to be filled with air to an Atmospheric orhigher pressure.
 5. A kinetic engine according to claim 1 wherein thefloat is centrally mounted on a sleeve, which is slidably mounted on thefixed shaft, the sleeve extending above the float to provide connectionto the power takeoff means.
 6. A kinetic engine according to claim 5wherein a power takeoff means incorporates a hydraulic or pneumatic ram.7. A kinetic engine according to claim 5 wherein the sleeve incorporatesgear rack means.
 8. A kinetic engine according to claim 7 wherein thegear rack means comprises a series of spaced circular grooves in aportion of the sleeve.
 9. A kinetic engine according to claim 7 or 8wherein the power takeoff means includes a gear means driven by the gearrack means.
 10. A kinetic engine according to claim 9 wherein the gearmeans includes an opposed pair of pinion gears driven by gear rackmeans, one of the pinion gears transferring power from an upstroke ofthe float and the other of said pinion gears transferring power from adownstroke of the float.
 11. A kinetic engine according to claim 10wherein each of said pinion gears has a respective pinion shaft, eachpinion being mounted on its shaft so as to drive rotation of the shaftwhen the pinion gear is rotated in one direction and to freewheel in theopposite direction.
 12. A kinetic engine according to claim 11 whereinsaid pinion shafts are connected via a jockey gear so as to rotate apower output shaft in a constant direction upon both upstroke anddownstroke of the float.
 13. A kinetic engine according to claim 1wherein the float has a chamber/chambers adapted to contain liquidweight media for the purpose of balancing forces of strokes, with saidliquid weight media being lifted to an uppermost position with notransfer of energy to the float or from the float during the upstroke,where potential kinetic energy of the said weight media is converted tomechanical energy during downstroke.
 14. The kinetic engine of claim 1wherein said openings are slots.
 15. The kinetic engine of claim 7wherein the sleeve and gear rack means are rotatably mounted to thefixed shaft.